Bro - take your time. If you're underlvl, you can ask some of the forum dudes and dudettes for their friend code, so you can have a strong helper squad to help

For Xmas event, you can just grind for cards on the lower lvl missions

I remember as a new player, I didn't finish the first July mission or Geranium's mission. That was okay. It took a month for me to atually clear events easily. This game is not that hard compared to other Nutaku games that requires a ton of grinding. I blew Flower Gems recklessly b/c I never found this site nor any other sites' beginner guide. Regret not hoarding Flower Gems.